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Photovoltaic modules must generally be connected in series in order to produce the voltage required to efficiently drive an inverter. However, if even a very small part of photovoltaic module (PV module) is prevented from receiving light, the generation power of the PV module is decreased disproportionately. This greater than expected decrease occurs because PV modules which do not receive adequate light cannot operate on the normal operating point, but rather operate as loads. As a result, the total power from the PV modules is decreased if even only a small part of the PV modules are shaded. In the present paper, a novel circuit, referred to as the generation control circuit (GCC), which enables maximum power to be obtained from all of the PV modules even if some of the modules are prevented from receiving light. The proposed circuit enables the individual PV modules to operate effectively at the maximum power point tracking, irrespective of the series connected PV module system. In addition, the total generated power is shown experimentally to increase for the experimental setup used in the present study. Index Terms-AC interactive inverter, multistage chopper, photovoltaic module.

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We propose a method to evaluate the carrier transport properties in the inversion layer of 4H-SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) experimentally. Our approach differs from conventional methods, which have adjusted the parameters in conventional mobility models. Intrinsic phonon-limited mobility (μ phonon ) in the SiC MOSFET was observed by suppressing the severe impact of Coulomb scattering on the SiC MOS inversion layer by lowering the acceptor concentration (N A ) of the p-type well region to the order of 10 14 cm −3 . In this study, we investigated the carrier transport properties in the inversion layer of Si-face 4H-SiC MOSFETs with nitrided oxide. It is revealed that the μ phonon of the SiC MOSFET is a quarter or less than the conventionally presumed values. Additionally, surface roughness scattering is found not to be the most dominant mobility-limiting factor even at high effective normal field (E eff ) for the SiC MOSFET. These results demonstrate that conventional understanding of carrier scattering in the SiC MOS inversion layer should be modified, especially in the high E eff region.

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Visible-light-absorbing, narrow-gap semiconductors have attracted significant interest in recent years owing to their photofunctional applications, including heterogeneous photocatalysis and solar cells. Herein, we report a new Pb-free perovskite material with a wide range of visible-light absorption that was successfully synthesized via hydride (H–)-ion doping into BaSn0.7Y0.3O3−δ. Chemical reduction that accompanied H–-ion doping significantly reduced the optical band gap of the host BaSn0.7Y0.3O3−δ from 4.0 to 2.0 eV. Physicochemical measurements revealed that BaSn0.7Y0.3O3−δ underwent the partial reduction of Sn4+ to Sn2+ at B-sites while maintaining the cubic perovskite structure. Density functional theory calculations showed that the electronic states derived from the Sn2+ lone pair, which was located above the top of the valence band, contributed to the visible-light absorption of reduced BaSn0.7Y0.3O3−δ. The prior introduction of oxygen defects into BaSnO3 by Y3+ substitution for Sn4+ was also indispensable to realize a significant reduction of the band gap. The reduced BaSn0.7Y0.3O3−δ doped with H– ions was applied as a photoelectrode material, and a clear anodic photoresponse of up to 600 nm was observed, which demonstrates that the material can be used for photofunctional applications. The results of this work suggest that the utilization of stereoactive lone pair of electrons in combination with H– doping may provide another approach to the band gap reduction of Sn­(IV)-based oxides, which are nontoxic and less expensive, but generally wide-gap semiconductors.